obslog: add display of precursor information to the default template This will still only be output when the user passes --precursors to the command (otherwise the data just won't be there). This addresses a common user request, where they actually would find more intuitive to use --precursors --no-successors.

obslog: add flags to control the output of precursors and successors With just this change, precursors are only shown in structured output.